1. Field of the Invention
The present invention relates to an imaging apparatus, and more specifically to an apparatus capable of switching an operation mode in accordance with a status of connection with a PC (personal computer), a printer, etc.
2. Related Background Art
Conventionally, a system for connecting a digital camera with an information processing apparatus such as a personal computer (PC), etc., via a cable, etc., so that the information such as image data, etc., recorded on a recording apparatus in the digital camera or on a record medium attached detachably to the digital camera can be transferred to the PC has been developed and introduced commercially (for example, Japanese Patent Application Laid-Open No. 2003-125271).
In recent years, a system in which a digital camera can be directly connected to a printer via a cable to attain printing without a PC has become commercially practical. In this case, there are different devices such as a PC and a printer to be connected to a digital camera. If an interface and a protocol which can be commonly used by these different devices in communication with a camera are available, the camera can communicate with these different devices without any problems.
Lately, a standard called “Pict Bridge” has been proposed as a system for communication between a camera and a printer which are directly connected.
In the version 1.0 of this standard, a camera is connected to a printer via a general-purpose bus of a type called “USB” (universal serial bus), and the printer functions as a host of the USB. Data exchange is performed using PTP (picture transfer protocol) as a communication protocol. The protocol is also a general-purpose protocol prescribed by the still imaging device class of the USB as a data exchange protocol for a PC and a camera.
Thus, a camera can communicate data through a common protocol independent of the type of device with which it is communicating (the “communicatee”). Using the Pict Bridge, data exchange called “service discovery” is performed in order to recognize whether the communicatee is a printer adaptable to the Pict Bridge. Through the data exchange, the printer and the camera recognize whether or not each other is adaptable to the Pict Bridge, and a service is offered by exchanging script data described in a data format predetermined by the Pict Bridge.
On the other hand, conventionally, when a camera is connected to a PC, the camera has normally been operated by the PC, and there is little opportunity to operate the camera itself. Therefore, except with a small number of digital cameras for professional use, a power saving effect has been expected by turning off the operation of the camera and the display device thereof in the PC connection mode when the camera is connected to the PC.
Digital cameras such as those for professional use can use a relatively large number of resources such as ROM, RAM, etc., in the camera, and a battery of a large capacity can be used. Therefore, when a PC is connected, no PC connection mode may be required in the operation of the camera. However, with a common compact digital camera, there are restrictions on the resources and power supply, and thus the resources of the ROM and RAM are saved by exclusively controlling the internal status, and no power is supplied to an inactive block, to save the power when the PC is connected.
Conventionally, different communication protocols have been used among manufacturers in connection to the printer and a digital camera and a printer therefore cannot be connected unless they are manufactured by the same manufacturer. However, there have been digital cameras operable by connecting them to the printer directly via USB by placing them in communication with a PC using the USB. In this case, since one protocol is used in a case in which the camera is connected to a PC and a different protocol is used in a case in which the camera is connected to a printer, it is necessary to implement a plurality of protocols in the camera. As described above, when there are a plurality of communication modes in a digital camera, it is necessary to switch over between them.
In the conventional system, as described above, different communication protocols are used for connection to a PC and a printer, or a unique protocol is used for each type of device. Therefore, it has been necessary to switch the communication mode when a digital camera recognizes that a device with which it needs to communicate is using a different protocol or when a communication mode switch command is received.
There is also a technology for making the operation of a camera valid under the control of a PC when the camera is connected to the PC, displaying an image, etc., on the display device implemented in the camera, and allowing a user to operate the member of a camera to transfer the image to the PC (for example, Japanese Patent Application Laid-Open No. 2002-133406, corresponding to U.S. Patent Application Publication 2002-063781).
Thus, the older method, of merely transferring image data in a camera to a PC which has conventionally been only an external apparatus for storage and browsing the image data, has been enhanced to a model that provides for operating the PC and the camera in cooperation.
However, as described above, in recent years, even if the digital camera is connected to the printer, the standard of data communications using a digital camera connected to external equipment has been standardized in many cases, so that the protocol used when a PC is connected can be used. In this case, the communicatee can be recognized only after discovery is performed for recognition of the communicatee defined with the standardized regulations.
Although there is little problem if all devices to which a digital camera is connected are in compliance with the Pict Bridge standard, an application having no relation with the Pict Bridge standard is connected in the current status of connecting to a normal PC. In this case, unlike the conventional cases, there is the problem that the camera cannot find the timing at which it is to enter a communication mode when it is connected to a PC. Otherwise, it is necessary for a user, before connection with an external apparatus, to select the setting of a digital camera to decide whether the digital camera is connected to a printer or a PC, and it is therefore necessary to connect the camera to the external device to change the process to be performed.
Furthermore, although a digital camera is connected to a device such as a PC, etc., there can be a case in which the communication mode of a camera is switched by an application running in the device. In this case, depending on the communication mode switch timing of the camera, it has become necessary for a camera to use a system which can effectively utilize minimal resources and save electric power.
Therefore, when a digital camera and an external device are connected to each other for communication, a more-detailed method of control in the camera is required.